A peptide microarray (also commonly known as peptide chip or peptide epitope microarray) is a collection of peptides displayed on a solid surface, usually a glass or plastic chip. Peptide chips are used by scientists in biology, medicine and pharmacology to study binding properties and functionality and kinetics of protein-protein interactions in general. In basic research, peptide microarrays are often used to profile an enzyme (like kinase, phosphatase, protease, acetyltransferase, histone deacetylase, etc.), to map an antibody epitope or to find key residues for protein binding. Practical applications include seromarker discovery, profiling of changing humoral immune responses of individual patients during disease progression, monitoring of therapeutic interventions, patient stratification and development of diagnostic tools and vaccines.
The assay principle of peptide microarrays is similar to an ELISA protocol. The peptides (thousands in several copies) are linked to the surface of a glass chip. This peptide chip can directly be incubated with a variety of different biological samples, such as purified enzymes or antibodies, patient or animal sera, cell lysates, etc. After several washing steps, a secondary antibody with the needed specificity (e.g., anti IgG human/mouse or anti phosphotyrosine or anti myc) is applied. Typically, the secondary antibody is tagged by a fluorescence label that can be detected by a fluorescence scanner. Other detection methods include chemiluminescence or autoradiography.
Therefore, a peptide microarray is a planar slide with peptides spotted onto it or assembled directly on the surface. Whereas spotting peptides with current techniques can undergo quality control prior to spotting and result from a single synthetic batch, peptides synthesized directly on the surface may suffer from batch-to-batch variation and limited quality control options. However, spotting peptides onto a support surface still has current significant limitations. One limitation is the large size of the peptide array required, which restricts its capability to be scaled up for proteomic measurements. A second limitation is that the peptide spotting output is often qualitative rather than quantitative. A third limitation is the high cost of peptide synthesis and limited access to the necessary instruments, which has prohibited its implementation as a routine technology. Other limitations exist in the current technology.
Therefore, there is a need to develop a peptide microarray technology that improves upon the prior art.